Cone loud-speaker



April 23, 1929.

R.L.W EGEL CONE LOUD SPEAKER Filed May 23, 1925 Patented Apr. 23, 1929.

UNITED STATES- PATENT OFFICE.

RAYMOND UIlilGflElIi, OF NEW YORK, N. Y., ASSIGNOB TO WESTERN ELECTRIC COM- IPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

CONE LOUD-SPEAKER.

Application filed Kay 23, 1925. Serial No. 32,899.

This invention relates to the construction of sound em1tting devices particularly of the type employing thin flexible material in the sound radiating member. More specifically t relates to a mode of construction whereby the light flexible material used in the radiator may be readily placed under stresses so as to increase the rigidity of the structure and improve the vibratory characteristics of the radiating surface. An object of this invention is to provide a mode of construction in which certain portions of the vibratory member are placed under stresses which enables the vibratory member to more faithfully vibrate throughout its entire area.

' Diaphragms or sound radiators are generally made of thin material and it is desirable that the material be of uniform thickness, free from distorting internal stresses, and possessed of various other internal characteristics which are uniform throughout so that sound vibrations may act upon the material with.

equal uniformity. It is practically impossible to obtain such material since in the process of manufacture of the paper, parchment or similar material, absolute uniformity in thickness cannot be obtained. Various stresses are material, varying degrees of hardness may exist, and where a material such as paper, is used, the direction of the fibre produces internal irregularities.

This invention provides means for neutralizing or counteracting certainof the bad effects inherent in the material used in making sound radiating surfaces. When a diaphragm is set in vibration certain areas, due to irregularities in the material, become resset up in the onant at different frequencies and under cer-' tain conditions these local resonant zones may vibrate with such a great amplitude as to cause severe distortions and disturbing noises. It has been discovered that this can be largely prevented by specially curving the diaphragm surface and several ways of accomplishin this are disclosed herein.

A su stantiall' plane surface made up of commercial gra e of paper or similar material when placed under vibration, would be quite subject to local disturbances of the above nature but if the same material is formed in the shape of a cone, an appreciable part of the disturbances is prevented. If the curve at its edges, a further improvement 1s made. Further correction of irregularities in the material may be made by corrugating the surface or by curving the entire surface. In particular, this invention provides a mode of changing the radius of curvature of a surface such as that of a coneby applying to the surface an adhesive coating such as a cement which contracts upon solidification and thereby produces stress causing bending. In accordance with a specific, application, two cones are cemented together at their peripheries by means of a cement which contracts upon solidification and puts the periphcry of both cones under a bending stress which augments the normal curvature of the conical surfaces in the neighborhood of their peripheries and this results in improving the sound radiating characteristics of the structure.

According to one feature of the invention corrugations are formed in the radiating material by placing a band of the adhesive cement of the proper width upon the material which upon solidification contracts and draws the material into a corrugated shape. The application of a number of parallel bands of the proper width and separation on the same side of a given surface will produce such corrugations or the corrugatlons may be produced by applying the cementing material alternately on opposite sides. The surface may also be bent by making success ve applications of the cementing material which shrinks upon solidification and the character of the resulting curvature may be controlled by the area over which the cement is applied.

Referring to the drawings, Fig. 1 is a side and part section view of a large cone type sound radiator.

Fig. 2 is a large section view showing the junction at the peripheries of the two cones before the cement is hardened.

Fig. 3 is a section view similar to Fig. 2

of the cement upon solidification when employed to cement a second member to the surface.

Fig. 6 is a section view of a conical diaphragm corrugated in accordance with this invention.

Fig. 7 is a section View of a conical diaphragm which has been curved by the application of a coat of adhesive cement whlch contracts upon solidification; and t Fig. 8 is a section view of a cone showing an augmented curvature secured by successive applications of cement over areas which progressively vary in width.

In most of these drawings the bend ng effect is exaggerated to more clearly bring out the action of the cement in bendin the surface upon contraction during solidification.

ent diameter so that one fits into the other when joined and cemented at their periphcries 15 and 16 by means of the eemcnt1ng1naterial 17. The cementing material not only attaches the two cones to each other but performs the important function of increasing the curvature near the peripheries and thus stiffens the structure.

When the peripheries of the two cones are placed together before cementing, the ele ments of the cones are straight lines as shown in Fig. 2. The cementing material 17 is shown here as it is placed before solidification and the elements 18 and 19 of each cone are straight lines from the apexes to the peripherie When the cementing material has solidified and contracted the peripheries of the cones are curved inwardly as shown in Fig. 3. The shrinkage of the cementing material bends the outer cone 15 inwardly and it in turn bends the periphery of the inner cone 16 also inwardly as shown in exaggerated detail in Fig. 3. It is thus obvious that the cementing material 17 not only I cements the periphcries of the two cones together but also pro-, duces the very desirable result of placing the peripheries under a sufficient compression and to slightly shorten the peripheries and bend the material so as to make the edges appreciably convex.

The result of placing a band of adhesive cement on a sheet of material which con tracts upon solidification is shown in Fig. 4. This curves the material and produces a corrugation substantially parallel with the axis of the band of cementing material.

Another method of producing a corrugation and stiffening of the material is shown in Fig. 5. A second piece of material 20, for example similar to that of the main material,

is placed upon the main surface normal to it and cement is placed in the angle formed at each side in contact both with the main surface and the auxiliary member 20. The cementing material upon solidifying contracts and exerts a pull on the material on each side of the member 20 thus bending the main sheet somewhat as shown.

A corrugated conical sound radiator is shown in Fig. 6. This structure is similar to that shown in Fig.1 with the exception that corrugations have been added by alternately applying bands of cement which contract upon solidification to bot-h sides of the two cones. The action of the cement in contracting curves the surface so as to produce corrugations as shown. Parallel corrugations similar to those shown in Fig. 6 may be produced by placing bands of the cement properly spaced only on one side of the cone instead of alternately on each side. Also non-parallel corrugations can be made if so desired by properly spacing and directing the band of cement.

A slight spherical curving of the conical surface may be secured as shown in Fig. 7 by completely coating one surface with cement which produces a shrinkage on one side which tends to curve the material. Another method of curving the surface is shown in Fig. 8 wherein successive applications of the cement in varying widths is made in such a way as to produce a greater and greater tension in the area where the greater number of applications of.,cement is made. The varying widths of cement and arrangement of the successive layers are shown by the several lines extending varying distances from the periphery towards the apex of the cone and the thickness of the layers is greatly exaggerated in the drawing.

The producing of curvature in the material and the setting up of stresses is brought about in accordance with this invention by the use of an adhesive cement which-contracts upon solidification. Similar effects may be brought about by using an adhesive cement which expands upon solidification, by properly designing the structure to use an expanding cement.

WVhat is claimed is:

1. The method of securing the peripheries of two conical surfaces together so as to augment the normal curvature of theconical surfaces in the neighborhood of their peripheries, comprising lapping one cone over the other and applying a contracting adhesive to the joined edges.

2. The method of increasing the strain throughout the area of a cone diaphragm so that such added strains at all points are large compared to the local strains existing in the material prior to this treatment, which consists in applying successively rings of ce ment which contract upon solidification.

, facing each 0t 3. The method. of obtaining tension in sheets of material comprising applying an adhesive to said sheets which contracts upon solidification to provide contracted areas in the material.

4. In a sheet of flexible material, means for introducing unidirectional bending strains to compensate for irregularities of strain or density or to increase its rigidity comprising a cement applied to portions of said material, which cement contracts upon solidifying.

5. In combination two conicaldiaphragms connected together attheir peripheries by a cementing material which contracts upon solidification and bends the cones inwardlynear their peripheries.

6. In combination, two conical diaphragms of slightly different diameters positioned together at their peripheries with the smaller within the lm er and with concave surfaces er, and means for cementing the, said cones together at their peripheries and for bending the surfaces of each cone inwardly at and near their peripheries comprising a cement applied at and adjoining the junction of the said cones which contracts 7 upon solidification. 1

' neighborhood of 7. Means for securing the peripheries of two conical surfaces together, comprising an adhesive cement which contracts upon solidification, said cement being applied along the peripheries so as to augment the normal curvature of the conical surfaces in the their peripheries 8. In an acoustic device a conical diaphragm, a frusto-conical support for said diaphragm, the peripheral dimension of which is less than the peripheral dimension of said diaphragm, a rigid support for said first named support and means at the peripheries of said diaphragm and said support for securing them together.

9. In an acoustic device, a diaphragm, a frusto-conical sup ort therefor, the. diameter of the base 0 said frusto-conical sup port being less than the diameter of said diaphragm, a rigid support for said first named support and means for joining said diaphragm and said support together at their peripheries. j

In witness whereof, I hereunto subscribe my name this '15 day of May, A. D. 1925.

RAYMOND L1 WEGELI 

